Carbonated beverages are ubiquitous in modern society. As the name indicates, such beverages are infused with carbon dioxide and maintained under pressure. Loss of carbonation causes a carbonated beverage to become stale or “flat”. Bottlers of carbonated beverages desire to know the rate of carbonation loss for its various bottled products as such information allows the bottler to determine the shelf-life of its products and test various bottle types and designs for their ability to retain carbonation.
Carbonated beverage bottles typically include a body portion, a neck portion that is narrower than the body, and a mouth atop the neck. The mouth of the bottle is closed with a twist-off or pry-off cap or closure after the bottle has been filled.
Carbonated beverages tend to lose carbonation through both the walls of the bottle body and neck, and through the cap or closure area of the bottle. Loss of carbonation through the bottle walls occurs by permeation of carbon dioxide through the walls. Loss of carbonation through the cap or closure area tends to occur by both permeation of carbon dioxide through the cap and leakage of carbon dioxide through the seal formed between the cap and the bottle.
Testing equipment has been developed for measuring a total rate of carbonation loss from a bottle, such as described in U.S. Pat. Nos. 6,964,191 and 7,624,622, and for ascertaining the rate of carbonation loss from permeation through the cap or closure area as a component of total carbonation loss from a bottle, such as described in U.S. Pat. No. 6,018,987. However, none of the testing equipment developed to date is capable of providing an accurate measurement of the effectiveness of a cap or closure to prevent loss of carbonation as the testing equipment measures the rate of carbonation loss through the cap or closure area while allowing a contemporaneous unmeasured lose of carbonation through the sidewalls of the bottle. By allowing a contemporaneous loss of carbonation through the bottle sidewall, a second variable is introduced (e.g., ΔP and ΔPCO2 across the bottle may vary from test to test), preventing the test data from serving as a true and accurate indication of transmission of carbon dioxide through the cap or closure area, and destroys the ability to directly compare test results.
Accordingly, a substantial need exists for testing equipment capable of accurately and reliably measuring the carbon dioxide transmission rate through the cap or closure area of a carbonated beverage bottle.